Benthic fauna in relation to pollution: A case study at River Chambal near Kota in Central India

The Chambal river, subjected to industrial and sewage pollution, was studied with reference to the benthic fauna. Twenty seven taxa of benthic fauna of four main groups were observed at the stretch of the river: Oligochaeta, Diptera, Mollusca and Insecta (“others”). It was noted that the pollution input zone shows less fauna. The analysis of various physicochemical parameters showed an increase in pollution where domestic and industrial effluent were added. Changes in the benthic community have been explained with the help of the Diversity Index. The species diversity values showed a decrease from the prepollution point to the effluent discharge channel with an increase at the posteffluent point, indicating it to be a recovery zone. The coefficient of correlation was assessed between different physicochemical and different groups of benthic fauna.     

A comparative study of the glutamate dehydrogenase activity in several species of marine phytoplankton

Kinetic studies on the NADP-linked glutamate dehydrogenase (GDH) activity in 8 species of marine phytoplankton have been carried out. The pH optima, linearity of reactions, apparent energies of activation, and apparent K _m values for NADPH, NH ₄ ^>+ and -ketoglutarate were determined. Based on these data, an accurate, sensitive enzyme assay procedure is presented which was successfully tested on shipboard during a recent cruise in an upwelling region. Preliminary studies on inhibition and activation of the NADP-linked GDH activity have also been carried out. In addition to NADP-linked GDH activity, NAD-linked GDH activity was discovered in certain species of phytoplankton. The possible physiological roles of NAD-and NADP-linked GDH enzymes are discussed.Contribution No. 911 from the Department of Oceanography, University of Washington. This research was supported by the National Science Foundation Grants GA-34165 and GX-33502.     

Generalized Nondimensional Depth‐Discharge Rating Curves Tested on Florida Streamflow1

Abstract: A discharge rating is a relationship between stage and discharge at a specific point in a river stream or lake outlet structure. Rating curves are useful for interpolating and perhaps extrapolating flow measurements and for use directly in storage routing models. However, rating data and stations are limited. A generalized nondimensional mathematical expression that describes the rating relation of depth and discharge has been developed and tested against observations from 46 stations in West‐Central Florida. Three approaches were tested in sequence to select the best fit. The proposed model is a log‐linear equation with zero intercept and a slope that fits more than 50% of the stations were analyzed. The model is normalized by the depth and discharge values at 10% exceedance from data published by the U.S. Geological Survey. For ungauged applications, Q₁₀ and d₁₀ were derived from a relationship shown to be reasonably well correlated to the watershed drainage area. The average relative error for this parameter set shows that for the flow range up to the Q₁₀ discharge, better than 30% agreement with the USGS rating data can be expected for about 50% of the stations. Further analysis is required to determine why so many stations exhibit such similar behavior and to identify the criteria or parameters governing the differences.     

Social support and managerial affective responses to job stress

This research examines the moderating or buffering effects of two social support variables—support from the work group and from the supervisor—on the relationships of role conflict and ambiguity to intrinsic job satisfaction, job involvement and job anxiety. Data were collected from a sample of 89 middle-lower managerial personnel in a large, heavy equipment manufacturing firm in the Midwest. The moderated regression technique was used in data analysis. Significant interactions were obtained between the role variables and both social support variables. The results were in the predicted direction for positive work outcomes (i.e. job satisfaction and involvement) and contrary to prediction for negative work outcome (i.e. job anxiety). Implications of the findings for future research, the management of stress and leadership behaviour are discussed.     

基于测试数据的室内超宽带信道建模研究

基于室内超宽带信道测量研究建立了基于簇的时延抽头模型以及与距离和载频有关的新颖的路径损耗模型,建立了路径损耗同时与距离和频率的依赖关系.同时,研究发现视距和非视距接收信号幅度分别满足莱斯和瑞利分布.该模型对超宽带无线系统仿真和设计有重要的指导意义.     

A system model for green manufacturing

Manufacturing systems evolution is afunction in multiple external and internal factors. With today’s global awareness of environmental risks as well as the pressing needs to compete through efficiency, manufacturing systems are evolving into a new paradigm. This paper presents a system model for the new green manufacturing paradigm. The model captures various planning activities to migrate from a less green into a greener and more eco-efficient manufacturing. The various planning stages are accompanied by the required control metrics as well as various green tools in an open mixed architecture. The system model is demonstrated by an industrial case study. The proposed model is a comprehensive qualitative answer to the question of how to design and/or improve green manufacturing systems as well as a roadmap for future quantitative research to better evaluate this new paradigm.     

Aging-independent and size-dependent genotoxic response induced by titanium dioxide nanoparticles in mammalian cells

Titanium dioxide nanoparticles(TiO_2 NPs) are subjected to various transformation processes(chemical, physical and biological processes) in the environment, potentially affecting their bioavailability and toxic properties. However, the size variation of TiO_2 NPs during aging process and subsequent effects in mammalian cells are largely unknown. The aim of this study was to illustrate the adverse effects of TiO_2 NPs in different sizes(5, 15 and 100 nm) during aging process on human-hamster hybrid(A_L) cells. There was an aging-time dependent enhancement of average hydrodynamic size in TiO_2 NPs stock suspensions. The cytotoxicity of fresh TiO_2 NPs increased in a size-dependent manner; in contrast, their genotoxicity decreased with the increasing sizes of NPs. No significant toxicity difference was observed in cells exposed to either fresh or 60 day-aged TiO_2 NPs. Both Fresh and aged TiO_2 NPs efficiently induced mitochondrial dysfunction and activated Caspase-3/7 in a size-dependent manner.Using mitochondrial-DNA deficient(ρ~0) ALcells, we further discovered that mitochondrial dysfunction made significant contribution to the size-dependent toxicity induced by TiO_2 NPs during the aging process. Taken together, our data indicated that TiO_2 NPs could significantly induced the cytotoxicity and genotoxicity in an aging time-independent and size-dependent manner, which were triggered by mitochondrial dysfunction. Our study suggested the necessity to include size as an additional parameter for the cautious monitoring of TiO_2 NPs disposal before entering the environment.